// Copyright 1999-2020 Alibaba Group Holding Ltd.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package base

import (
	"sync"
	"sync/atomic"
	"unsafe"
)

const mutexLocked = 1 << iota

// The mutex which supports try-locking.
type mutex struct {
	sync.Mutex
}

// TryLock acquires the lock only if it is free at the time of invocation.
func (tl *mutex) TryLock() bool {
	return atomic.CompareAndSwapInt32((*int32)(unsafe.Pointer(&tl.Mutex)), 0, mutexLocked)
}
